1. Field of the Invention
The invention relates to a semiconductor device. More particularly, the invention relates to a semiconductor device in which a diode region and an insulated gate bipolar transistor (hereinafter, IGBT) region are formed on the same semiconductor substrate.
2. Description of Related Art
Japanese Patent Application Publication No. 2011-129619 (JP 2011-129619 A), for example, describes a semiconductor device in which a diode region and an IGBT region are formed on the same semiconductor substrate. In this semiconductor device, a crystal defect region is formed in a drift region of the diode region. When a reverse recovery operation is performed in the diode region, carriers in the drift region recombine with crystal defects in the crystal defect region and disappear, thus making it possible to improve the switching speed.
With the semiconductor device described in JP 2011-129619 A, while the diode region is off and the IGBT region is on, some carriers within the drift region may flow into an anode region, and leak current may flow into the diode region. Also, if a large number of carriers are generated from the crystal defect region due to a temperature increase or the like, a large leak current may flow to the diode region.